Add changelog entry

Author: Turbo87

axum-core/CHANGELOG.md

@@ -9,6 +9,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 # 0.5.0
 
+- **change:** The `Display` impl of all rejections generated by the
+  `define_rejection!()` will now include the `Display` output of the
+  inner error too. This matches the `body_text()` fn output now. ([#3118])
+
+[#3118]: https://github.com/tokio-rs/axum/pull/3118
+
 ## rc.1
 
 - **breaking:**: `Option<T>` as an extractor now requires `T` to implement the